Executive Summary : | Cycloparaphenylenes (n-CPP) are cyclic conjugated molecules in which the phenyl rings are connected at p-positions and are connected back to form a hoop like structure. Their cyclic conjugation, radially oriented pi-orbitals and the pore size makes them unique carbon materials. Perovskite Solar Cells (PSCs) have their advantages over the Si-based solar cells in terms of cost of production, environmental aspects, and appearance. Efficiencies of PSCs increased greatly with the introduction of organic small molecule Hole Transporting Material (HTM). Spiro-MeOTAD is the most used HTM, but have limitations like high cost of synthesis, low conductivity and low hole mobility and it requires additional p-type dopants to perform better. This hinders the device stability and increases the cost further. Spiro-Xanthene (SPX) having a Spiro core is considered as a low cost and easy to synthesize alternative to Spiro-MeOTAD. The power conversion efficiencies (PCE) of PSC using SFX based small molecules reported over 19%. So far, linear conjugated molecules have been used as HTM for PSC applications. Literature survey suggests that the orbital energies of CPP’s meets the requirements needed to be used as HTM. An all Carbazole CPP has been used as an active material in Organic Field-Effect Transistor (OFET) with decent hole mobility. Based on the literature reports an SPX-Carbazole CPP can be assumed to be having all the necessary requirements to be used as HTM. Computational studies revealed that optoelectronic properties of CPP can be altered by changing the positions of the functional groups and by increasing the ring size. Based on these reports, three SPX-Carbazole CPP has been proposed with altering positions of Carbazole units. It would be interesting to study the changes in optoelectronic properties of these derivatives and their potential application in optoelectronics especially as HTM for PSC applications. It is also worth noting that the cavities of these CPP can be used for host-guest studies. Further, to develop Spiroxanthene-carbazole based cyclic conjugated molecules featuring different hetero- or polycyclic aromatics end groups. |